camera_fuzzer: Fix fd handling for native_handle_t object

Resolved `fdsan: attempted to close file descriptor`
error by properly opening file descriptors in
CameraFuzzer::createNativeHandle. This ensures file
descriptors are correctly assigned in native_handle_t
objects used in camera_fuzzer.

Test: ./camera_fuzzer
Bug: 335562493

Change-Id: I393b7c8160520b3b0ba1d3d1d377c6980232fae8